Black Small Worms on the Sand

[elijah090622]

Need ID this black hair like small worms all over my tank. Like hundreds of them. I searched everywhere and couldn’t find anything, even use AI. They only appear when lights are off hiding from the sand and disappear with lights on.

 

[Tahoe61]

I have no idea, but I would hazard to guess the population is regulated by the available food resource. For instance if you have a Bristle Worm population and you over feed the tank will end up with a lot more Bristle Worms.
Did you start the tank with live rock?

 

[lilzman8]

You might be overfeeding the tank allowing them to swell in numbers, black bristle worms